I'd always wondered what it must feel like to be faced with a radical new set of ideas, for example, people 80-120 years ago with the "atomic" age. I feel that total confusion with this. Many of the ideas around atoms have been simplified enough for schoolchildren to understand now. I wonder if schoolchildren in 100 years from now will find quantum mechanics and instantaneous transportation similarly rudimentary and easy to understand.
> I wonder if schoolchildren in 100 years from now will find quantum mechanics and instantaneous transportation similarly rudimentary and easy to understand.
They will. And, to some extent, they will be wrong. There's nothing rudimentary about a nuclear reactor, yet indeed the basic concepts are now available for a bright primary school student to grasp.
I think we just got better at creating a more accessible mythology that stands in place of rigorous math for the laypeople.
Right. Well, what I had in mind was the huge pile of sterile discussions on topics such as black holes, speed of light, quantum mechanics, etc, that one could see all the time on... well... just about any forum online. And most of the comments during such a discussion are... I would not even call them "wrong", you'd need at least some relation to reality to earn this badge. They're more like pure fantasy, unhinged.
For those people, modern science has replaced mythology.
But I agree with you. Pop science, correctly done, is heavily indebted to analogy.
> I wonder if schoolchildren in 100 years from now will find quantum mechanics and instantaneous transportation similarly rudimentary and easy to understand.
Possibly, but I doubt they'll ever find it intuitive. The fact is, we build up our intuition on the "macroscopic" scale, and that just doesn't apply at the quantum scale. So there'll always be a level of weirdness when you learn about it for the first time regardless of how much further our theories advance beyond what we know now.
This is a good point. Newtonian mechanics is fairly simple to understand because it operates at scales and velocities we are familiar with. Hell, I'd say you can grok a lot of it by throwing stuff in the air and thinking carefully about what happens.
On the other hand, I'm reminded of the following lecture by Brian Cox. He explains the double-slit experiment, draws things on a board, shows a really nice physical demonstration with water, and.... the person on stage is still completely lost: http://youtu.be/PaGwpbHJWGE?t=1m54s
I'm not sure how much better that could possibly be explained.
I do not think the current teleportation is instantaneous, as that would require baffling the intuition of even the physicists that think about teleportation every day.
Also: IF (write that in large font, bold, in capitals) teleportation at macroscopic scales becomes common, say with schoolchildren going to a disco on The moon or on Mars every weekend, they will rapidly build up their intuition around such things, just like the current generation is quite used to "going to Madrid/New York for a weekend".
I don't think that quantum mechanics is going to be rudimentary and easy to understand for schoolchildren unless we have some pretty massive overhauls of mathematics education.
I've tried dropping fundamentals of quantum mechanics on my kids so that it doesn't seem so alien to them. I still have trouble grokking the spooky-action-at-a-distance experiments, but I know what the punchline is.
If you understand the Everett interpretation, those experiments stop being spooky-action-at-a-distance. Instead they become a prediction about a system at one locality will interact with a system at another locality when they rejoin.
The trade-off is that your picture of reality has to become much weirder.
I'm not a big fan of the Everett interpretation. It seems too contrived. I prefer to think of spooky-action-at-a-distance as the nature of the wavefunction is such that its domain is all particles in the universe (which it is, since splitting it up for single particles is an approximation). Problem solved.
I do not understand what you think is contrived about it. To me the assumption that quantum mechanics does not describe the human brain is much harder to swallow than the Everett interpretation is.
> None of those challenges seem like showstoppers. Which means that practical quantum routers and the quantum internet that relies on them are just around the corner.
I've been hearing about qubits for awhile now and don't really understand the significance of having quantum entanglement in a network. Can you entangle multiple clients in a mesh, and add or remove entanglements? Is that even possible in the future with this?
Or can you manufacture entanglement with each connection, where you initiate the entanglement with a client, and maintain that connection during transport? I'm really just curious if you can use this technology, and literally replace the methods of connections and transport as we use them now, or if this is simply a single function method.
> You can have perfectly encrypted communication that no one can eavesdrop on (not even theoretically).
That is an interesting observation because there is a flip side to it. I can sell you some ordinary looking gear that contains a quantum entanglement based eavesdropper. You can have your device in a cave 20 miles below the earth's surface in a bunker running off diesel generators, with no connections outside the bunker, and here I am, watching everything you do.
I think you are right that this is probably the primary advantage, but this article keeps talking about "quantum information" and not entanglement. Can this actually send quBits or just bits?
> You can have perfectly encrypted communication that no one can eavesdrop on (not even theoretically).
Not exactly. Quantum "cryptography" assures you that only one party received the data, but not who that other party is. There is no authentication. To prevent a man in the middle attack, you have to use a conventional message authentication code, and the system as a whole is no stronger than the MAC algorithm.
You can transport quantum states with quantum networks. So you can do a quantum computation in one place, transmit the quantum data somewhere else, do more processing, etc. and then only measure & collapse the waveform when you're done.
Note that this is "teleportation" of quantum information and not teleportation of matter. To the layman, referring to this sort of thing as teleportation seems a bit misleading to me.
Quantum teleportation does not allow for faster-than-light information transition.
While changing particle A makes particle B change, the second's information can't be understood without transmitting a third piece of information from A to B.
Does that mean that Quantum teleportation will never have practical applications? If you need to send a third piece of information at the speed of light or slower, why not send all your information through that channel?
From what I've been reading it's mostly for security, not speed. Using Quantum teleportation, nobody can get any useful data from intercepting that third piece of information.
Even if it's not faster than light I'm hoping for teleportation that means no line of sight required and distance boundless wireless transmission. I could totally settle for that.
I need to catch up on my quantum physics, every time I read that someone pulled off quantum teleportation I'm disappointed when I read the line "here we realize quantum teleportation between two remote atomic-ensemble quantum memory nodes, each composed of 100 million rubidium atoms and connected by a 150-meter optical fiber" taken from the source article. http://arxiv.org/abs/1211.2892
I know there's a difference between what they did and regular fiber optics. It just doesn't seem to be quite the same. Can it be done without the interconnecting material? If not it's really useless. When I picture practical uses of quantum teleportation I picture things like rovers instantly sending data and receiving instructions.
>When I picture practical uses of quantum teleportation I picture things like rovers instantly sending data and receiving instructions.
That won't happen. It's impossible to transmit classical information faster than light via quantum teleportation. You don't necessarily have to have "interconnecting material", but there will always have to be a classical information channel, and that will always be light-speed bound.
I don't think it's useless. As I understand, quantum teleportation would allow for a massive increase in bandwidth. That's a pretty good result, and who knows, maybe they'll get rid of the interconnecting cables in the future, as well.
I wonder if in 50 years only quantum physicists will truly understand how technology works. Perhaps the days of cheap tinkering with electronics are numbered, in the future requiring multi-million dollar quantum labs.
This is how things have been in the physical science fields. Chemistry, biology, you name it--capital intensive.
The computing and theoretical fields (so long as they're non-experimental and require no more than simple simulations) are the exception to the rule rather than the rule itself.
Also, until a space is commoditized, working in it is expensive and time-comsuming.
Thirty years ago, the most advanced multi-million dollar laboratory in the world would not have been able to understand or tinker with the computer you're sat at currently.
I think it'll be more akin to the situation with through hole and SMD components. The former allowed one to tinker with PCBs with a simple soldering iron, while the latter require a reworking station no matter what you want to do.
Thankfully, these stations have dropped in price a lot - you can easily buy a good one for ~$200-300, which would allow you to repair your phone, modify your motherboard, resolder memory chips and whatnot...
Will Quantum Teleportation, if possible, let us reduce, if not remove, the hardware for communications? As in, there will be no need for giant fiber-optic cables or wireless routers?
no, there's still a huge confusion out there towards what constitutes quantum teleportation. all I can say as a layman is that this title is very misleading, you still need a standard information channel to transport the information about a single qubit. wikipedia has more: http://en.wikipedia.org/wiki/Quantum_teleportation
That closing line is a bit optimistic: “Which means that practical quantum routers and the quantum
internet that relies on them are just around the corner.”
I have no idea how this whole thing works (quantum mechanics, entanglement, "teleportation"), still there are news all over saying it's the future.
I shouldn't need a degree in Physics to understand how it works. Is it really that complicated and magical, or is it still so barely understood that no one can explain in simple terms?
It depends how deep an understanding you want. You don't need a degree in Physics, but if you want anything more than a superficial idea then you do need degree-level knowledge of the necessary maths and physics.
I don't need a degree in Physics to understand Newton's laws, even though I couldn't derive these laws on my own. Heck, the explanation fits in three lines, and it explains a ton of things.
That's the kind of understanding I mean. It seems there isn't one concise, simple explanation for these effects. I wonder if it's because the reasoning behind it is that complex that you need to resort to esoteric math and abstractions (in which case, the current theories might be crude, Occam's razor and all), or if it's because no one truly comprehends it enough to explain concisely.
By the way, I picked up Leonard Susskind's lectures to watch. It was all fine up to special relativity - his explanation about frames of reference was so obvious, it just made sense. After that, though, nothing made sense anymore.
Newton's Laws fit into three lines because most of us are already familiar with the integral concepts: force, mass, inertial reference frames, etc. The concepts involved in quantum mechanics are fairly alien to most people, so explaining the theory takes longer. The fundamentals of orthodox QM can be fit into three principles: 1) The Time-Dependent Schrödinger Equation; 2) The Time-Independent Schrödinger Equation; and 3) The Born Rule. Even writing these out in full doesn't take long. Explaining what they mean, however, can take a while.
Frames of reference are fairly obvious in SR. In General Relativity they're more non-trivial.
Many of the ground-breaking research and the research papers I study for my Physics term papers originate from Chinese Scientists. I just mean Chinese Scientists appear more frequently and this is a perfect example.
China isn't the only one conducting this kind of ground breaking research, but they do put a lot of money into it. I don't have any numbers, but I wouldn't be surprised if China's investment in research was higher than most other research countries.
Can someone with physics knowledge tell me the difference between quantum entanglement and the following example:
2 pens spinning in exact opposition, one clockwise the other anticlockwise, are hurled from a space ship in opposite directions. You do not look at them when you are doing this. When a pen is found light years away, that person instantly knows how the pen on the other side of the universe is spinning and in what phase.
No teleportation has actually taken place. Information has not been transferred faster than the speed of light. This assumes that pens travel through empty space and do not interact with things that would affect their rotation or movement.
I'll venture for an answer: none. The moment you decide to check for a pen, you sealed his fate ( ie. which rotation it has ) and also of the other pen. So to say, you collapsed his wave. Kind of a Schroedinger's cat experiment.
The reason you know about the both pens in the moment you look at them is, well, because they are "entangled". But no information has been sent. You had this information all along with you, bound by the space-time and it's C speed limit.
The scenario you outlined is quite important and actually has a name: it's the "Bertlmann's Socks" thought experiment, and if you want to read about it I'd seriously recommend the paper by the great J S Bell[1].
To use the language of your example, both pens begin in a superposition of clockwise and anti-clockwise. It's not the case that each pen has a particular spin value, and that we're simply unaware of which has which. The pens really are in a superposition.
Until, that is, a measurement is made on one of them. At this point the joint pen-pen system collapses and both pens have determinate spin values. The nature of the entanglement ensures that those spin values are different.
The notion that quantum-entangled particles could have well-defined properties that we're just ignorant of was actually pretty popular in the early days of quantum mechanics. In fact, the theory was put forward by Einstein, among others. As it turns out, however, that we can test for this. The tests have been done, and it seems Einstein was wrong on this one.
[1]: J. S. Bell (1980), "Bertlmann's Socks and the Nature of Reality"
Cool. But what if the two pens are spun randomly in a box by say a random number generator spinner (each is pen is still anti-correlated - you just don't get the spin) - such that you do not know that what state they are in (superposition?). Then, probabilistically, they are both clockwise and anti-clockwise - until of course you look at it, a point at which they "snap" to a specific spin (which they already were in? You just didn't know it yet). Wouldn't that give you your unpredictable states.
I'm sorry if this sounds stupid - I just want to understand.
It's not stupid - the difference between uncertainty and superposition is subtle. Let's simplify to the case of one pen.
Say the pen is spun in the box by a classical random number generator. You don't know which way the pen is spinning, but you do know that it's either been spun one way or the other. You might say that the probability of finding it spinning clockwise when you open the box is 1/2.
Now say the pen is prepared in a superposition of the two spin states, again in the box. As before, we might say that the probability of discovering the pen spinning clockwise is 1/2. However, this time we the probability isn't generated by our lack of knowledge: we know exactly what state then pen is in. When we open the box, however, the pen will change instantly to the state of spinning clockwise, or the state of spinning anti-clockwise.
In the quantum case, the probability is an expression of what we think will happen to the pen, not what we think has happened to it.
It is hard to grasp, and harder still to believe. There is, however, good reason for thinking that, sometimes, the pen changed just as we opened the box.
